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// This source code is released into the public domain.
module;
#include <filesystem>
#include <optional>
#include <ranges>
#include <paths.h>
#include <unistd.h>
export module nihil.posix:find_in_path;
import nihil.error;
import :fd;
import :getenv;
namespace nihil {
/*
* Find an executable in $PATH and return the full path. If $PATH is not set, uses _PATH_DEFPATH.
* If the file can't be found or is not executable, returns std::nullopt.
*/
export [[nodiscard]] auto
find_in_path(std::filesystem::path const &file) -> std::optional<std::filesystem::path>
{
using namespace std::literals;
auto try_return = [](std::filesystem::path file) -> std::optional<std::filesystem::path> {
auto ret = ::access(file.string().c_str(), X_OK);
if (ret == 0)
return {std::move(file)};
return {};
};
// Absolute pathname skips the search.
if (file.is_absolute())
return try_return(file);
auto const path = getenv("PATH").value_or(_PATH_DEFPATH); // NOLINT
for (auto &&dir : path | std::views::split(':')) {
// An empty $PATH element means cwd.
auto sdir = dir.empty() ? std::filesystem::path(".")
: std::filesystem::path(std::string_view(dir));
if (auto ret = try_return(sdir / file); ret)
return {ret};
}
return {};
}
} // namespace nihil
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